NET ZERO ENERGY DESIGN

NET ZERO ENERGY DESIGNA GUIDE FOR COMMERCIAL ARCHITECTURE

Tom Hootman

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Library of Congress Cataloging-in-Publication Data:

Hootman, Thomas. Net zero energy design : a guide for commercial architecture / Thomas Hootman. p. cm. Includes bibliographical references and index. ISBN 978-1-118-01854-5 (cloth); ISBN 978-1-118-34516-0 (ebk); ISBN 978-1-118-34517-7 (ebk); ISBN 978-1-118-34848-2 (ebk); ISBN 978-1-118-34849-9 (ebk); ISBN 978-1-118-34850-5 (ebk) 1. Commercial buildings—Energy conservation. 2. Commercial buildings—Environmental aspects. 3. Architecture and energy conservation. I. Title. TJ163.5.B84H66 2013 690’.520286—dc23 2012002033

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

Cover image: NREL/PIX 17613; photograph by Dennis Schroeder

To Jackson and Ray Hootman, for their—

and our world’s—net zero energy future. Here comes the sun.

■ vII

TABLE OF CONTENTS

■    ACKNOWLEDGMENTS IX

In     INTRODUCTION XIII

My Net Zero Energy Journey XIII

How To Use This Book XIV

Ov CHAPTER 1: NET ZERO ENERGY BUILDING

OVERVIEW 1

The Case for Net Zero Energy Buildings 1

Defining Net Zero Energy 4

Classifying Net Zero Energy Buildings 10

Alternative Approaches to Net Zero Energy 12

Certifying Net Zero Energy Buildings 15

Building Industry Research and Trends 16

Building Industry Programs 19

Building Industry Codes and Regulations 20

Building Rating and Energy Labeling Systems 23

PC CHAPTER 2: PROJECT CONCEPTION AND

DELIVERY 27

The Net Zero Energy Objective 27

Project Conception 36

Project Planning 40

Project Team Selection 44

Delivery Methods 49

Risks and Rewards 53

IP CHAPTER 3:  INTEGRATED PROCESS 57

Integrated Delivery and Management 57

Project Delivery Phases 63

Integrated Design Methods 69

Building Energy Modeling 73

En CHAPTER 4: ENERGY 89

Energy Basics 89

Energy Use Intensity 102

Energy Targets 109

Energy and Thermal Comfort 125

DF CHAPTER 5: DESIGN FUNDAMENTALS 133

Energy Design Conditions 133

Climate Assessment 133

Site Assessment 158

Building Massing and Geometry 166

Building Type and Zoning 177

PA CHAPTER 6: PASSIVE ARCHITECTURE 183

Passive Design 183

Design Science 186

Building Envelope 202

Passive Strategies 215

EE CHAPTER 7: ENERGY-EFFICIENT BUILDING SYSTEMS 231

Active Systems 231

Basic Concepts 235

HVAC Overview 240

Low-Energy Distribution 243

Low-Energy Primary Equipment 247

Domestic Hot Water 256

Lighting 258

District Energy 266

RE CHAPTER 8: RENEWABLE ENERGY 271

Renewable Energy Basics 271

Solar Power 272

TABLE OF CONTENTSvIII ■

Solar Thermal 284

Wind 293

Hydro 300

Geothermal 306

Biomass 309

Fuel Cells and Hydrogen 314

Ec CHAPTER 9: ECONOMICS 319

Financial Considerations 319

Financial Models 329

Financial Analysis 333

Net Zero Energy and the Real Estate Market 341

OO CHAPTER 10: OPERATIONS AND

OCCUPANCY 347

Building Operation 347

Plug Loads 352

Green Behavior 357

Net Zero Energy Performance Plan 363

NZ CHAPTER 11: NET ZERO ENERGY 367

Net Zero Energy Balance 367

Net Zero Energy Measures 367

Carbon Neutrality 377

CS CHAPTER 12: CASE STUDY: DOE/NREL

RESEARCH SUPPORT FACILITY 387

Introduction 387

Process 388

Project Economics 389

Climate, Site, and Program 391

Design Response 394

Operation and Occupancy 406

Performance Metrics 411

■    BIBLIOGRAPHY 417

■    ABOUT THE AUTHOR 427

■    INDEX 429

ACKNOWLEDGMENTS ■ Ix

ACKNOWLEDGMENTS

This book is important to me. I believe it can play a meaningful role in moving our industry toward a new way of designing and delivering buildings—toward net zero energy architec-ture. In the process of writing Net Zero Energy Design: A Guide for Commercial Architecture, I was fortunate to be supported by a remark-able network of like-minded, passionate indi-viduals—colleagues, friends, and family—who also believe in the book and the objective of achieving net zero energy buildings.

I would first like to thank my wife, Deonne Hootman, for being the ultimate support system. She not only took up all of the slack around the house, enabling me to work count-less hours without worry or distractions, she also served as a fantastic sounding board for my ideas, and often had just the cure for any case of writer’s block. Thanks also to my two children, Jackson and Ray, and to my parents and sister for their support, and for under-standing my crazy writing schedule.

I would next like to thank my contribut-ing authors, Shanti Pless, from the National Renewable Energy Laboratory (NREL), and David Okada, who worked at Stantec while contributing to this book and is now with Integral Group. Both were instrumental in the success of the Department of Energy/National Renewable Energy Laboratory (DOE/

NREL) Research Support Facility (RSF); they are also passionate and accomplished leaders and experts in net zero energy buildings. This book would not have been possible without their contributions. I am grateful for their hard work and the sacrifices they made to help make this book a reality.

I am fortunate to work at RNL, where net zero energy architecture has become part of our daily practice, and where there is a strong focus on developing the next generation of architecture. I would like to thank everyone at the firm for being supportive of the book and my process of writing it, and specifi-cally, for fostering the kind of creative culture that inspires such undertakings. Thanks to RNL’s CEO, Josh Gould, for his enthusiasm and encouragement during the production of this book, as well as for his tolerance of the demanding schedule I had to maintain to complete the manuscript. Thanks as well to Leslie Alpert and Sarah Rege for their per-sonal support; they stepped in when neces-sary to keep my projects moving forward when I took time off from them to work on the book. Thanks also to Lisa Glass, for her always-keen writing advice and help in pulling together some of the images for this book. And to Tom Wuertz, for his assistance in providing content from the Eastside Human

ACKNOWLEDGMENTSx ■

Services Buildings, a net zero energy-ready building, which could be one of our next zero energy buildings.

I am also grateful to Alecia Huck of Maverick & Company, who has worked with me as a leadership and presentation consul-tant. She has helped me hone and craft the net zero energy story, particularly in regard to the Research Support Facility project. She has also helped me recognize, and embrace, the important leadership role required to get this message out.

The experience of delivering the Research Support Facility sparked the inspiration for this book. The entire project team, while not all listed here, was made up of some of the most talented and hard-working profession-als I have ever worked with. I would like to thank the entire team, and then single out the following individuals from RNL’s inter-nal team of architects, interior designers, and landscape architects: Rich von Luhrte, Craig Randock (now with HDR Architecture), Michael Simpson, Allison Menke, Nathan Gulash, Rachel Petro, Wendy Weiskopf, Michelle Richter, Brian Nicholson, and Steve Breitzka. From Stantec I thank David Okada (now with Integral Group), John Andary (now with Integral Group), Porus Antia, and Lloyd Mariner. From Haselden Construction, I thank Phil Macey, Byron Haselden, Brian Livingston, and Jerry Blocher; and Dana Villeneuve, from Architectural Energy Corporation.

There is a tremendous amount of truth in the saying that it takes a great client to design a great building. The DOE/NREL has been an exceptional client. The profession-als there have a strong vision for the future of high-performance buildings, and they wanted their project to show the way to this future. We were fortunate to partner with them along this journey. In the process of deliver-ing the Research Support Facility, I came to

be friends with many of the talented staff in the NREL Advanced Commercial Buildings Research Group, many of whom have been instrumental in the development of this book. Thanks to everyone at DOE/NREL, not only for making the Research Support Facility a reality, but for your ongoing research and the development of tools and resources needed by the industry to make a net zero energy future possible. Specifically, I am grateful to Jeff Baker, Bill Glover, Drew Detamore, Ron Judkoff, Paul Torcellini, Shanti Pless, Eric Telesmanich, Bret Cummock, Peter McMillin, Nancy Carlisle, Karen Leitner, Jennifer Scheib, Nicki Johnson, Michelle Slovensky, Frank Rukavina, Rob Guglielmetti, Chad Lobato, Greg Stark, Nick Long, and David Goldwasser.

I thank, too, all of the professionals in the industry who are working hard to make net zero energy buildings a mainstream reality. I interviewed several key individuals from both the owner and developer perspective, as well as from an energy modeling viewpoint. Highlights from these interviews are featured throughout the book. Thanks to Donald Horn of the General Services Administration, Richard Kidd of the U.S. Army, Chris Rogers of Point32, Linda Morrison of Ambient Energy, and Porus Antia of Stantec.

I also conducted many informal inter-views, and had numerous discussions and exchanges with various experts in the field, all of which helped me develop specific content areas of the book. It is through their generos-ity, their willingness to spend time with me and share their knowledge, that I was able to gather the most current and innovative ideas about the myriad challenges and opportuni-ties inherent in any net zero energy project. In this regard, I thank Rachel Petro of RNL, Dean Stanberry of Jones Lang LaSalle, Paul Means of Davis Graham & Stubbs, Ken Urbanek of

ACKNOWLEDGMENTS ■ xI

MKK Consulting Engineers, Cathy Higgins of the New Buildings Institute, and David Lehrer of the Center for the Built Environment.

I want to express appreciation, as well, to everyone who provided the remarkable photographs and images in the book, which do so much to tell the net zero energy story. Notably, Frank Ooms and Ron Pollard, two of the most talented architectural photographers RNL has worked with, graciously granted per-mission to include many of their exquisite pho-tographs of the DOE/NREL Research Support Facility; Tania Salgado and Pat McKelvey, friends and coworkers at RNL, shared a few of their personal architectural photographs, taken during their extensive travels; and Lisette Lebaillif, a photographer from Dallas/Fort Worth, captured a stunning image of the Kimbell Art Museum, designed by Louis Kahn. Thanks also to all of the talented staff and contract photographers at NREL, and to Mike Linenberger and Shanti Pless for facilitating the use of many photographs from the NREL PIX collection.

I am grateful also to the many firms and individuals who contributed photos and images of their own work. They include Erin Lawrence of The Kubala Washatko Architects, Dawn Porcellato and Ray Sinclair of RWDI, Erin Gehlr of BNIM, Tiffany Lee of Buro Happold, Kevin Nance of Adrian Smith + Gordon Gill Architecture, Doug Spuler of the Beck Group, Jill Badenhop of Westlake Reed Leskosky, Manfred Starlinger, and Martin Read of Colt International and Mike Allen of AWV Architectural, Porus Antia and Liesel Wallace of Stantec, Linda Morrison of Ambient Energy, Tracy Becker and Steve Comstock of

ASHRAE, Molly Canales of Weber Shandwick for Bloom Energy, Chris Rogers of Point32, Matt Ellis and Nick Alexander of U.S. Army Corps of Engineers at Fort Carson, Dr. Murray Peel of the University of Melbourne, Michael Holtz of LightLouver, and Gavin Platt of Lucid Design Group. I appreciate both your com-mitment to contributing quality work and your willingness to share it with me for this book.

In many ways, Net Zero Energy Design began with a coincidental airport reunion I had in 2010, with Jim Leggitt, an architect and Wiley author whom I have known for years. We were both traveling to Miami for the AIA convention and he encouraged me to con-sider writing a book. He also introduced me to John Czarnecki, who was, at the time, an editor at Wiley and in Miami for the conven-tion. Subsequently, I began writing my book proposal, for which I enlisted help and feed-back from Jim Leggitt, Daniel Tal, and Annette Stelmack, all friends and Wiley authors. Thanks to all of you, for your support, encouragement, and great advice.

Finally, I thank John Wiley & Sons, spe-cifically publisher Amanda Miller, for seeing the value and need for this book within the industry, and for making it a reality. I’m grate-ful to Kathryn Bourgoine, who stepped in when John Czarnecki left Wiley to become the editor-in-chief at Contract magazine. She did a fabulous job as I was putting the finishing touches on the manuscript. I’m also grateful to Mike New and Danielle Giordano for helping me through the publishing process. And finally, thanks to Donna Conte, the senior production editor, who masterfully guided the manuscript and artwork through production of the book.

Image courtesy of RNL; photograph by Frank Ooms.

INTRODUCTION ■ xIII

INTRODUCTION

MY NET ZERO ENERGY JOURNEYIn my role as director of sustainability at RNL, I have been very fortunate to be involved in a world-changing architectural project. It is the project that inspired the writing of Net Zero Energy Design, and the project that sharply focused the commercial building industry on the goal of achieving net zero energy buildings. This project has been profiled by and featured in building industry conferences across the nation, and covered by building industry media, as well as national publications such as the Wall Street Journal and the New York Times. Metropolis magazine defined it as a game-changer for 2011, by taking net zero energy to scale. The

project I am referring to is the Department of Energy’s (DOE) Research Support Facility (RSF) at the National Renewable Energy Laboratory (NREL), shown in Figure I.1.

This project demonstrated not only that net zero energy is viable for large-scale commercial buildings, but that it also adds unique value to them. Furthermore, the proj-ect revealed the gaps in current conventional building delivery processes, gaps we will need to fill if we are to develop net zero energy solutions. It is one aim of this book is to help fill these gaps in our process—specifically, to answer the question: How do we deliver a net zero energy commercial building?

In

 ■ FIGURE I.1 DOE/NREL Research Support Facility. Image courtesy of RNL; photograph by Frank Ooms.

INTRODUCTIONxIv ■

My involvement in the DOE/NREL Research Support Facility project influenced me greatly; and the “fingerprints” of this project can be seen throughout this book, whether in specific examples from the project or in the form of a general influence on how the delivery process must be retooled. I have been inspired by the amazing results achieved by the project, espe-cially by all the extraordinary individuals on the delivery team who made them all happen. That team included talented professionals from RNL, Stantec, Haselden Construction, and a host of capable and quality design consultants and subcontractors. As you can imagine, hav-ing the Department of Energy and the National Renewable Energy Laboratory as a client pur-suing net zero energy in a large office building was a profound experience (see Figure I.2). NREL is a remarkable resource for low-energy and net zero energy buildings, supporting some of the best research and thinking in the world. I have come to believe that NREL is one of the nation’s best-kept secrets. In sharing the story of this project with thousands of people in the building industry, I was always surprised by how many were unaware of NREL, one our greatest energy resources. I am certain the DOE/NREL Research Support Facility will do remarkable work in advancing the mission of DOE and NREL, and I sincerely hope that this book will do its part to move our industry to net zero energy.

HOW TO USE THIS BOOKThe purpose of Net Zero Energy Design is to serve as a design and delivery guide for net zero energy commercial buildings. What distin-guishes this book from other sustainable design guides is its singular focus on reaching net zero, coupled with a dedication to the entire compre-hensive process it takes to get there. Success for a net zero energy building is rooted in the

holistic process, from the conception of the proj-ect to its ongoing operation. It’s not just a design problem; it’s an entire delivery problem, one that includes the building’s occupancy and opera-tion. Therefore, this book is meant to advance the most important aspects of each part of the delivery process as it relates to achieving net zero energy. Thus, because the focus is on the entire delivery process, Net Zero Energy Design is not intended to serve as a highly detailed technical guide to specific issues within the delivery process; there are many excellent books and resources available that offer focused guid-ance on the individual efforts needed to execute the numerous individual net zero energy deci-sions within the process.

Net zero energy buildings are challenging to complete, and each project has unique issues that must be wrestled with. This book does not aspire to address all conditions and circum-stances that a net zero energy building might face. In this sense, then, the book is not an instruction manual; it does not offer a process that guarantees a net zero energy building. Nor is the content of this book meant to replace the expert judgment of design professionals. The book is based on my personal project experi-ence and my ongoing research into the net zero energy process, supplemented by the valuable contributions of my invited contributors, Shanti Pless and David Okada, who share my driving desire to advance a net zero energy building practice. It is written from the point of view of a practitioner, and meant to convey information useful in practice.

Therefore, in it, I have made a conscious effort to introduce tools and resources that I use and am familiar with; I also attempt to set them within the context of their implementation in actual practice. I also mention several software programs that have been valuable to me and, I believe, might be useful to others. Such mention

INTRODUCTION ■ xv

 ■ FIGURE I.2 DOE/NREL Research Support Facility. Image courtesy of RNL; photograph by Frank Ooms.

INTRODUCTIONxvI ■

is not, however, intended as an endorsement, or meant to imply that there are not other appli-cations available that satisfy the same need. I also include content on software tools, though I recognize that this information will be outdated at some point in the near future—to be super-seded, I hope, by more powerful and capable programs than those currently available.

As an architect I have come to realize that we in the profession have a unique role in making net zero energy architecture possible; we must assume a leadership role in order to transform our industry and the built environ-ment. Furthermore, as a profession, we have some changes to make. Most important, we need to take ownership of the energy design problems inherent in our projects, rather than relegating them to the engineers and energy modelers. As such, though this book is tar-geted in large part at architects, it is also meant as a guide for all those involved in the entire process of delivering a net zero energy building. My goal is that the content will have value for everyone in the building industry.

Thus, while focused primarily on the com-mercial building sector, many of the ideas and principles presented can be readily applied to the residential sector as well.

And to ensure that the book has something to offer those who are new to the field, as well as those who have substantial experience, I have intentionally provided key introduc-tory concepts as primers for more detailed understanding and project application, and to assist new practitioners in expanding their net zero energy knowledge base. The seasoned practitioner will benefit from the perspective I offer on the delivery process. For the reader’s convenience, I have also compiled essential resources for net zero energy building delivery, to serve as an ongoing project reference.

The book is organized around the net zero energy project delivery process, hence can be used as a road map to help each practitioner develop his or her own process. The chapters address, in turn, each stage in the process, and are generally sequential in terms of the overall delivery process of a net zero energy project.

Chapter 1: Net Zero Energy Building OverviewChapter 1 provides an overview of net zero energy buildings. It defines them, makes the case for them, and discusses the current trends in the building industry.

Chapter 2: Project Conception and DeliveryChapter 2 captures the owner’s perspective on net zero energy buildings and explains how the net zero energy objective can be integrated into the early concep-tion of a project. It also addresses the variety of delivery methods available in the industry, and the impact they can have on this objective.

Chapter 3: Integrated ProcessChapter 3 presents the delivery team’s perspective on delivering a net zero energy project and introduces the specific issues in the integrated process that can assist in delivering the project.

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INTRODUCTION ■ xvII

Chapter 4: EnergyChapter 4 is a primer on energy concepts. Having a strong foundation on energy principles is a prerequisite to designing and delivering a net zero energy project. This chapter also focuses on the practical application of energy in the process, including setting an energy target.

Chapter 5: Design FundamentalsChapter 5 describes the fundamental principles that need to be established and understood before the design of a net zero energy project can begin. It offers a per-spective on climate analysis and site assessment, and explains building geometry, massing, and building typology, as related to the pursuit of net zero energy.

Chapter 6: Passive ArchitectureChapter 6 stipulates that net zero energy design starts with the architecture. It explores the role passive design strategies play in reducing energy loads in a building.

Chapter 7: Energy-Efficient Building SystemsChapter 7 offers guidance on how to efficiently meet the reduced loads of a passively designed building with low-energy building systems.

Chapter 8: Renewable EnergyChapter 8 introduces the various renewable energy systems available for a project and explains how they can be integrated with the design of a net zero energy project.

Chapter 9: EconomicsChapter 9 takes a close look at the economics behind net zero energy buildings. The focus is on understanding and analyzing energy efficiency and renewable energy systems.

Chapter 10: Operations and OccupancyChapter 10 tackles one of the most important aspects of a net zero energy building: its operation and use. Because a net zero energy building is measured in actual opera-tion, thoughtful consideration of this factor is critical. This chapter works to bridge the gap between design intent and the realities of building operation.

Chapter 11: Net Zero EnergyChapter 11 serves to synthesize the preceding chapters, in order to derive a final cal-culation methodology for measuring a project’s net zero energy balance. The chapter also provides a framework for understanding and evaluating carbon neutrality for a building project.

Chapter 12: Case Study: DOE/NREL Research Support FacilityRecognizing that, often, an actual example is the best way to learn about and advance the practice of net zero energy delivery, Chapter 12 presents the DOE/NREL Research Support Facility project as a case study.

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INTRODUCTIONxvIII ■

Of course, in practice, the delivery process is not strictly sequential, but rather may be itera-tive and cyclical in nature. Therefore, the book may be approached in much the same way: It may be read from start to finish, or approached from a number of different pathways through the book. The chapter “road map” shown in Figure I.3 suggests how the chapters may be organized based on their focus on guidance, design issues, or process issues.

 ■ Chapters 1, 4, 11, and 12 are dedicated to overall guidance for net zero energy; they provide definitions, fundamental concepts, and an overall synthesis of concepts.

 ■ Chapters 5, 6, 7, and 8 provide design guidance; as such, they may be regarded as the core chapters of the book.

 ■ Chapters 2, 3, 9, and 10 give process guidance for net zero energy commercial buildings.

One of the ways I have found effective to introduce net zero energy as a concept to new audiences is through a simple conceptual equation, which states that net zero energy equals the accumulation of passive design plus energy-efficient building systems plus renew-able energy systems, all over an integrated pro-cess. The chapters of this book then may be seen as the building blocks of this conceptual equation, which is shown Figure 1.4.

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INTRODUCTION ■ xIx

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 ■ FIGURE I.4 Net Zero Energy Concept as an Equation.

THE CASE FOR NET ZERO ENERGY BUILDINGS ■ 1

CHAPTER 1

NET ZERO ENERGY BUILDING OvERvIEW

THE CASE FOR NET ZERO ENERGY BUILDINGS

A Global SolutionThe twenty-first century is shaping up to be a transitional era for the way humanity dwells on this earth. The pressure we are placing on the planet’s resources has become increasingly unsustainable. The resulting problems we face, such as water and resource scarcity, increas-ing energy demands and costs, shrinking fos-sil fuel reserves, and a changing climate, have sounded a wakeup call heard round the world. Those who are heeding the call and embracing the need for change are finding in the neces-sary solutions opportunities not only to address this global set of problems but to advance and improve humanity’s relationship with the living world, and improve our quality of life.

Much of the stress we impose on the earth is manifested in the way we design, construct, and use our built environments; that means buildings and cities must play a vital role in shaping our sustainable future. Net zero energy buildings are tools in shaping this future. The buildings themselves offer significant environ-mental, social, and economic value. They are as much representatives of a global approach to our built environment as they are exemplary buildings (see Figure 1.1). The lessons they can

teach us about the power of integrated design and delivery, and about the true interconnec-tivity between our built environment and the natural world, can be applied to a diverse range of sustainable solutions, such as net zero waste and sustainable water balances in buildings and communities.

There is a powerful synergy between net zero energy objectives and other holistic sus-tainable goals. They all require a focus on performance and an integrated delivery pro-cess. The benefits of a holistic approach are, themselves, synergistic. Many strategies that reduce energy use can also have a positive impact on indoor environmental quality and, thus, the health and well-being of occupants. The net zero energy approach can be taken to any scale and positively affect the way we build and live in communities and cities.

A vision for the FutureNet zero energy buildings offer a compel-ling vision for the future, a vision that can be seen as a new direction in architecture. The pursuit of this vision can be technically rigorous; moreover, it requires tremendous creativity and innovation in design. As such, it offers an opportunity for new expressions of form to elegantly resolve energy solutions with program, site, and climate. Net energy

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CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW2 ■

design is an architecture that rediscovers the passive strategies of our architectural history and then integrates them into current ideas about contemporary design. It also embraces the best of state-of-the-art technology and renewable energy systems to provide solu-tions that set new standards for building and occupant performance.

Net zero energy architecture is also about process, one that requires genuine and intense integration, and takes a long view of the idea of building delivery. The integrated process can lead to the creation of truly holistic buildings, for net zero energy buildings should be more than just exemplary energy performers; they should embrace sustainability, performance, and beauty as well. They should actively work to enhance the human experience and, by

connecting to the larger systems of nature, enhance all life. Net zero energy architecture is part of a larger movement to design regen-erative buildings, buildings that are part of our living world.

As a new architecture, net zero energy uses data-driven and performance-oriented innova-tion to yield new forms. It also explores innova-tive, living connections to a building’s place, its climate, and the people who occupy it. It offers an opportunity to create beauty and meaning in our lives and in our communities. Beauty is particularly important for net zero energy buildings, because beautiful buildings tend to endure and be preserved, in addition to adding cultural and social richness. Net zero energy architecture must, therefore, be as beautiful and meaningful as it is pragmatic and high-performing; most important, it must have a higher purpose. In sum, net zero energy archi-tecture presents a vision for building a better and more sustainable future (see Figure 1.2).

The Time Is NowNet zero energy architecture is not an idea for the distant future; it is an idea whose time is now. We have the technology and the knowledge to delivery net zero energy com-mercial buildings today. What we lack, more than anything, is the collective imagination to make it happen. It is an objective of this book to spark the reader’s imagination and to help industry professionals adopt a net zero energy approach to buildings.

The fact that net zero energy buildings are possible today does not mean there are not challenges. Perhaps the greatest perceived chal-lenge is cost; but I would argue that the great-est actual challenge is the process to achieve a net zero energy building, as it is rigorous and requires change across the industry. Change is always difficult, particularly for such a change-resistant industry as the building industry.

 ■ FIGURE 1.1 View of New York City skyline, with

4 Times Square in the center. This building was an early

adopter of integrated renewable energy systems in a

high-rise.

THE CASE FOR NET ZERO ENERGY BUILDINGS ■ 3

Yes, cost can be a hurdle, but cost can be effectively managed with the right integrated delivery process. While it is possible to pay the way to net zero energy by purchasing more renewable energy and layering in more expen-sive and cutting-edge technology, it is also possible to manage costs effectively by inte-grating simple solutions that address multiple problems and do the hard work of reducing a building’s loads, thereby minimizing the invest-ment needed in renewable energy systems.

The many benefits of pursuing net zero energy buildings make the challenges worth taking on. Net zero energy buildings have eco-nomic, social, and environmental benefits, and represent a new standard for high-performing buildings, offering the greatest building and market value and, at the same time, the lowest life-cycle costs. These buildings can offer higher-quality interior environments that enhance quality of life for their occupants. They also lead to pro-found environmental benefits related to energy and resource conservation and the dramatic reduction of greenhouse gas emissions. Not only

are these benefits tangible today, they also make the case for a solution that addresses human-ity’s larger global challenges, and hence point to a better future (see Figure 1.3).

Needless to say, net zero energy buildings do not appear overnight. Because net zero energy is such a long-term goal and process, the industry to date has recorded very few buildings with verifiable data of one year or more of net zero energy performance. But the number of proven examples will grow over time and add to our knowledge of how to achieve this challenging goal. At the same time, net zero energy is an idea bigger than a narrow group of exemplary, high-performing buildings. Net zero energy should, therefore, be adopted as an approach to delivering all buildings, Whether or not they hit the zero target over time may be less important than the energy performance and the integrated on-site renewable energy solutions that can consistently be developed as part of our built environment. Ultimately, all buildings, including existing buildings, have the potential for net zero energy future.

 ■ FIGURE 1.2 DOE/NREL’s Research Support Facility provides a blueprint for a net zero energy future. NREL/PIX 17613; photograph by Dennis Schroeder.

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW4 ■

DEFINING NET ZERO ENERGYAt its core, net zero energy is a measure of a building’s energy performance, whereby it produces as much or more renewable energy as it uses over the course of a year in opera-tion. Two key concepts make up this defini-tion of net zero energy. First, net means that nonrenewable energy sources (fossil fuel and nuclear) may be used; but over the course of a year, enough renewable energy must be generated so that the project can offset or exceed the use of nonrenewable energy. The concept zero energy does not mean that the building uses no energy; rather, it refers to reaching a net zero energy position for build-ings that have full program demands. The second key concept is operation. Net zero energy is an operational goal. The period for measuring performance is one year of opera-tion, to include all seasonal variations. It is

possible to demonstrate a net zero energy in design. In fact, this is part of the process to achieve net zero energy. But a true net zero energy building must be achieved through actual measured operation.

The use of the word operation in the defini-tion changes the approach to net zero energy, indicating that it involves delivery of the project, not just design. At the same time this expands the process, it also enforces a more integrated process overall by aligning owner, occupants, operations, and construction and design profes-sionals around delivery. Designing for net zero energy is only one stage; actually operating as a net zero energy building is the real objective. Operation also means that the performance results in actual, quantifiable benefits—real car-bon emission reductions and real cost savings.

Net zero energy buildings are, first and fore-most, very low-energy buildings. The emphasis

 ■ FIGURE 1.3 The Omega Center for Sustainable Living is net zero energy and one of the world’s first certified Living

Buildings. Image courtesy of BNIM; photograph © 2009, Assassi.

DEFINING NET ZERO ENERGY ■ 5

on this point is important. The intent of reaching net zero energy is not to secure enough renew-able energy for a project regardless of energy efficiency. This is an inelegant and extremely expensive solution. A net zero energy building is a very low-energy building with enough dedi-cated renewable energy generation to meet its energy requirements over the course of a year.

The National Renewable Energy Laboratory (NREL) has defined four ways of measuring and defining net zero energy for buildings: net zero site energy, net zero source energy, net zero energy emissions, and net zero energy cost (see Figure 1.4). The NREL paper, “Zero Energy Buildings: A Critical Look at the Definition,” by Paul Torcellini, Shanti Pless, Michael Deru, and Drury Crawley, published in 2006, introduced these standardized definitions. Having an estab-lished definition and methodology for measuring net zero energy is key if the industry is to be able promote and communicate the metric in a unified

way. (A more detailed explanation of site energy versus source energy is provided in Chapter 4, along with other energy terms used in net zero energy definitions. The calculation methodologies for net zero energy buildings and the concept of carbon neutrality are explored in Chapter 11.)

Net Zero Site Energy BuildingA net zero site energy building produces at least as much renewable energy as it uses over the course of a year, when accounted for at the site. The measurement at the site is quite literal; that is, if a boundary is drawn around a building site, and all of the energy within the site boundary is measured and added up, the result is a site energy mea-surement (see Figure 1.5). This is the most commonly used and understood measure of net zero energy, because it reflects what would be recorded at the meter, and is easier to account for because it does not need the

Net Zero Site Energy

Net Zero Source Energy

Net Zero Energy Emissions

Net Zero Energy Cost

 ■ FIGURE 1.4 Net Zero Energy Building Definitions.

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW6 ■

additional factors required of the other mea-sures of net zero energy. That said, net zero site energy can be one of the most difficult of the four definitions to achieve, which makes it a good standard for measuring performance.

Net Zero Source Energy BuildingA net zero source energy building produces or purchases at least as much renewable energy as it uses over the course of a year, when accounted for at the energy source. This measure includes factors related to providing energy to a site. For example, it takes about three times the energy, in terms of coal-fired,

grid-based electricity, measured at the source as compared to what is actually delivered and measured at the site. Why? Because numerous losses result from generating and transporting electricity, as shown in Figure 1.6. Thus, source energy gives a more complete picture of energy use. In order to estimate source energy use, however, a site-to-source energy factor must be determined for each energy source used and applied to the site energy value.

Net Zero Energy Emissions BuildingA net zero energy emissions building pro-duces or purchases enough emissions-free

Site

Bou

ndar

y

Energy Sources Entering Site

Energy Consumed On-site

Natural Gas Electricity

Net Site Energy = 0

Net Zero Site Energy

Solar Energy

Net-metering

Energy Generated

On-site

 ■ FIGURE 1.5 Net Zero Site Energy Diagram.

DEFINING NET ZERO ENERGY ■ 7

renewable energy to offset emissions from all energy used in the building over the course of a year. Whereas site and source energy are measured in energy units, energy emissions is measured in mass of carbon-equivalent green-house gas emissions related to the energy use of the building. To determine the quantity of energy emissions, a carbon emission fac-tor must be applied to the site energy use for each energy source or fuel used for the

project, as shown in Figure 1.7. In this calcula-tion, renewable energy generation can offset emissions from fossil fuel.

The definition of net zero energy emission is an important one because it quantifies the key value of a net zero energy building: the elimina-tion of greenhouse gas emissions from build-ing operational energy. This definition provides one way to consider a building carbon-neutral for building energy operation. (A more detailed

Source Energy Factor 3.34Heat energy lossTransmission lossesPower used at plant

Source Energy Factor 1.047Transmission leaksPower used in process

Natural Gas Electricity

Site

Bou

ndar

y

Energy Sources Entering Site

Energy Consumed On-site

Natural Gas Electricity

Net Source Energy = 0

Natural Gas Gathering/Processing Electric Power Plant

Net Zero Source Energy

Net-metering

Energy Generated

On-site

Solar Energy

 ■ FIGURE 1.6 Net Zero Source Energy Diagram.

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW8 ■

discussion about carbon neutrality is presented in Chapter 11.)

Net Zero Energy Cost BuildingA net zero energy cost building receives at least as much financial credit for exported renewable energy as it is charged for energy and energy services by the utility over the course of a year (see Figure 1.8). There are

several parameters that need to be tracked to adhere to this definition. On the utility cost side, there are the rate structure for energy use, peak demand charges, fees, and taxes. Some utilities charge using rate structures based on time of use, which also would need to be factored in. In short, to arrive at this measure, all energy and energy service charges on the utility bill should be

Carbon Emission Factor 0.689 CO2e/MWH(National Average)

Carbon Emission Factor 0.0066 CO2e/MWH

Natural Gas Commercial Boiler Electricity

Site

Bou

ndar

y

Energy Sources Entering Site

Energy Consumed On-site

Natural Gas Electricity

Net EnergyEmissions = 0

Natural Gas Gathering/Processing Electric Power Plant

Net Zero Energy Emissions

Net-metering

Energy Generated

On-site

Solar Energy

 ■ FIGURE 1.7 Net Zero Energy Emissions Diagram.

DEFINING NET ZERO ENERGY ■ 9

included. The parameter that needs to be tracked on the credit side is the value cred-ited by the utility company for any renewable energy exported to the grid. Ideally, on-site renewable energy would offset a significant portion of the energy use before grid-based electricity is used, and would also offset peak demand. However, renewable energy generation is highly variable and so may not match up consistently in real time with energy use and peak demand. To achieve this definition, it is likely that the project will need to implement effective demand reduc-tion strategies and demand management systems.

Each utility company will have its own net-metering policies that define how on-site renewable energy generation is credited. Net metering allows meters to run both forward and backward, depending on whether the building is importing grid-based electricity or exporting on-site renewable energy. True net metering permits a one-to-one exchange of imported and exported electricity, thereby cred-iting renewable energy at the same retail rate charged for electricity imported from the grid. However, some utilities will switch from crediting at retail rates to wholesale rates for any excess renewable energy exported on an annual basis, or sometimes on a monthly basis.

Site

Bou

ndar

y

Energy Consumed On-site

Natural Gas Electricity

Net EnergyCost = 0

Net Zero Energy Cost

Solar Energy

Net-metering

Energy Generated

On-site

UTILITY

 ■ FIGURE 1.8 Net Zero Energy Costs Diagram.

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW10 ■

Ultimately, the way to demonstrate net zero energy cost is through actual utility bills. In fact, this cost can be relatively simple to verify, because the utility company makes the cal-culation. On the other hand, it can be hard to predictably meet this measure from month to month or year to year because of changes in utility rates and variations in monthly power demand. These variations also make the measure hard to plan for and to estimate, as discussed in Chapter 11. It also makes it chal-lenging to properly design a renewable energy system that makes it possible to consistently meet this measure, year after year.

It’s also important to point out that the defini-tion of net zero energy cost does not give the entire economic picture of a net zero building. The measure accounts strictly for the net cost of nonrenewable energy use. One important element outside of this measure is the invest-ment in the renewable energy systems. Just as a net zero energy building still uses energy, a net zero energy cost building will still incur renewable energy costs. (Chapter 9 focuses on the economic analysis of a net zero energy building.) One of the main values of this mea-sure is that it identifies a key value of a net zero energy building: energy cost savings. Moreover, it focuses attention on management of peak demand as part of the overall strategy, which the other three definitions do not address.

CLASSIFYING NET ZERO ENERGY BUILDINGS Having standardized definitions and meth-odologies for measuring net zero energy in a building is essential for giving the industry a unified approach to designing these buildings and then measuring the results of their actual operation. That said, there are many ways of getting to a net zero energy building within all four of the definitions given in the previous sec-tion, and they are not equitable or often even

comparable. How, for example, do you compare a building that achieves net zero energy with renewable energy generated by on-site systems to one that achieves this objective using renew-able energy generated off-site or through pur-chased renewable energy certificates?

Anticipating this issue, NREL, after pub-lishing the four definitions of net zero energy buildings, followed up in 2010 with a technical report outlining a classification system for net zero energy buildings, titled “Net-Zero Energy Buildings: A Classification System Based on Renewable Energy Supply Options,” by Shanti Pless and Paul Torcellini.

NREL’s classification system has four classes, A through D, and prioritizes the application of renewable energy to place a greater value on high-priority renewable energy applications. The system also grants buildings that may have diffi-culty achieving net zero energy the option to reach it at some level. The NREL system, which should be used in conjunction with the four definitions, enables a building to achieve one or more at a specific classification level per definition achieved.

Furthermore, the NREL classification system emphasizes demand-side reduction as a pre-requisite, to reflect the important necessity of a net zero energy building to be a very low-energy building. The system then prioritizes the appli-cation of renewable energy based on its type and location relative to the building. The clas-sifications also generally quantify the difficulty of meeting net zero energy with the renewable energy application under consideration.

Renewable energy applications range from providing all needed renewable energy systems within the building footprint (Classification A, or NZEB:A) to supplementing on-site renew-able energy with purchased renewable energy certificates to satisfy a net zero energy build-ing definition (Classification D or NZEB:D). Note that NZEB stands for “net zero energy building,” and the notation “NZEB:classification” is used

ALTERNATIVE APPROACHES TO NET ZERO ENERGY ■ 11

Net Zero Energy Classification System

Classification ASummary: A low-energy building with enough renewable energy generation from sources located within the footprint of the building to achieve one or more of the four definitions for net zero energy. This classification applies only to individual buildings.

Example Scenarios ■ Photovoltaic systems mounted on the building roof or façade. ■ Solar thermal systems mounted on the building roof or façade. ■ Wind turbines mounted to, or integrated into, the building.

Classification BSummary: A low-energy building with enough renewable energy generation from sources located within the project’s site to achieve one or more of the four definitions for net zero energy. The definition of site boundary is to include campus scenarios where the renewable energy systems are located on commonly owned contiguous property (easements are per-mitted to separate commonly owned property). This classification may apply to individual or multiple buildings.

Example Scenarios ■ Photovoltaic systems mounted over parking areas, or ground-mounted.  ■ Solar thermal systems ground-mounted on the site. ■ Wind turbines on towers mounted on the site. ■ Biomass harvested on-site and used to generate energy on-site.

Classification CSummary: A low-energy building that first utilizes renewable energy sources within the foot-print of the building and on-site, to the extent feasible, then imports enough off-site renew-able energy used to generate energy on-site to achieve one or more of the four definitions for net zero energy. This classification may apply to individual or multiple buildings.

Example Scenarios ■ Biomass imported on-site and used for electricity generation. ■ Biomass imported on-site and used for thermal energy generation.

Classification DSummary: A low-energy building that first utilizes renewable energy sources within the foot-print of the building and on-site to the extent feasible, then optionally imports off-site renewable energy used to generate energy on-site, but purchases off-site renewable energy to achieve a source or emission definition for net zero energy. This classification cannot achieve a site or cost definition of net zero energy. This classification may apply to individual or multiple buildings.

Example Scenarios ■ Purchased renewable energy certificates (RECs).

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW12 ■

within NREL’s classification system. A number of different renewable energy applications are available between these two extremes. Perhaps, for example, the renewable energy system is installed on-site or on a campus, not on the building itself (Classification B, or NZEB:B). Or an off-site renewable energy source such as biomass is imported (Classification C, or NZEB:C). Classification A is the most chal-lenging because it requires a net zero energy building to manage all of its needed renew-able energy within its own footprint. It is worth the effort, however, because earning this Classification A designation has intrinsic value, in that the renewable energy systems are inte-grated into the building and will likely serve the structure for the life of the renewable energy system. Such may not be the case for renew-able energy systems installed on a site, which can be removed or may end up shaded when new buildings or additions are added to the site.

The highest classification earned by the proj-ect’s renewable energy resources becomes the designation used for the project. Renewable energy resources from higher classifications may, however, be used to contribute to meeting a lower classification designation. For example, if the project does not have enough build-ing mounting photovoltaics to meet a net zero energy definition for classification A, the com-bination of site-mounted and building-mounted photovoltaics may be used to meet a net zero energy definition for classification B. A more detailed summary of the system follows.

ALTERNATIvE APPROACHES TO NET ZERO ENERGY

Off-Grid Net Zero Energy BuildingsOff-grid net zero energy buildings represent a unique application, and as such can be dif-ficult and, often, impractical to achieve for a commercial building. However, in cases where

conventional utilities are unavailable or very costly to bring to a project site, an off-grid solu-tion may be very appropriate. Off-grid net zero energy buildings are prohibited from using fossil-fuel-based energy sources because they have no way of offsetting such use by exporting renewable energy to the grid. And because an off-grid net zero energy building relies completely on on-site renewables, it meets all four defini-tions of net zero energy and, hence, exceeds the requirements of the various classifications.

The challenge with the off-grid net zero energy building approach is that because of the dynamic and variable nature of on-site renewable energy, some type of energy stor-age would be required to maintain building operation when renewable energy generation is lower than needed. Furthermore, off-grid net zero energy buildings may need additional renewable energy systems to handle peak loads. Finally, the combination of extra renew-able energy capacity and on-site storage must be carefully managed, as both extra capacity and storage are significant cost issues.

Using the grid (if available and feasible) to manage the surplus and shortage of energy needs for operating a net zero energy building has some distinct advantages. It reduces first cost and the need for batteries or other forms of energy storage, along with their related environ-mental and maintenance issues. It also allows the export and use of excess renewable energy within the grid, resulting in an increase in dis-tributed renewable energy available to the grid as more net zero energy buildings are brought online. This also has implications for smart-grid applications, which could add other benefits in regard to how on-site renewable energy, as well as energy use and peak load, are managed. Ultimately, as energy storage becomes more sophisticated and cost-effective, it may play a key role in energy management and backup energy in grid-connected buildings.

ALTERNATIVE APPROACHES TO NET ZERO ENERGY ■ 13

Partial Net Zero Energy BuildingsThere are several versions, or hybrids, of net zero energy buildings that do not meet the actual operational objective but are driven by the same goals and have very low energy use and a substantial infrastructure of renew-able energy systems. Partial net zero energy buildings, while lacking the prestige of fully meeting the net zero objective, are still notable achievements, as they require the same inte-grated process to develop, and result in a large number of the same benefits.

NEAR NET ZERO ENERGY BUILDINGSAs noted previously, the net zero energy objec-tive is challenging to meet. It has an absolute measure and can be verified year after year. With a factor as absolute as zero, it is either met or it isn’t. That said, approaching net zero also has tremendous value, and falling short of absolute zero should not be considered a fail-ure. Buildings that come close, or fail to achieve the status every year, should nevertheless be recognized as outstanding energy performers. Some in the industry call these buildings near net zero energy buildings.

NET ZERO ELECTRICITY BUILDINGA hybrid of net zero energy is the net zero electricity building. This type of building has a number of environmental and cost benefits even though it does not qualify as a net zero energy building. In a net zero electricity build-ing, the nonrenewable electricity use is zero or less over the course of a year, while other nonrenewable energy sources are not offset through renewable energy. The various mea-sures of site energy, source energy, energy emissions, and energy cost can be used to define a net zero electricity position.

NET ZERO ENERGY-READY BUILDINGA net zero energy-ready building, or net zero capable, is a building designed as a net zero

energy project but with the renewable energy systems deferred; they are not installed as part of the project. Without question, the financ-ing and procurement of the renewable energy system adds new challenges to the entire process of procuring a building or undertaking a major renovation of an existing building; and in some cases, it may be desirable, though not feasible, to procure the renewable energy systems. In such cases, the project can be designed for future integration of renewable energy systems. That means the systems should be planned to meet the net zero energy goal when installed, and the building should be designed for easy addition of the new systems by installing the necessary infrastructure, such as conduits, equipment areas, and structural capacity. If renewable energy systems cannot be installed initially, there is still tremendous value in making the project renewable energy-ready (see Figure 1.9).

Net Zero Energy for Multiple Buildings, Campuses, and CommunitiesSometimes, the right scale for net zero energy is not an individual building, but multiple buildings with a net zero energy solution. There are a vari-ety of circumstances where this could be advan-tageous. Every building has its own obstacles and challenges to achieving net zero energy. It may be that the building has a high energy use intensity (EUI), or lacks a roof and site area for renewable energy systems such as photovoltaic (PV) (see Figure 1.10). Grouping adjacent build-ings together may make it possible to balance out individual obstacles. In this way, a building with a high EUI can be grouped with neighbor-ing lower EUI buildings; and an available area for renewable energy systems can be shared as well. Such a strategy is ideal for moving more challenging buildings into a net zero energy posi-tion. (Chapter 4 defines and details the uses of the EUI metric.)

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW14 ■

There are additional synergies for grouping multiple buildings for the purpose of meeting net zero energy and other performance objec-tives. On mixed-use projects there may be opportunities to balance energy and thermal loads between uses. Scaling for multiple build-ings can also make a district-level sustainable infrastructure more efficient and economically feasible. Often, the project scope does not include multiple buildings; nevertheless, it may present a good opportunity to influence future master planning and to evaluate neighboring existing buildings for renovation opportunities and possible inclusion in the net zero energy objective.

Master planning and urban design projects for communities, neighborhoods, or cities can also take advantage of a net zero energy approach. In fact, planning for energy and renewable energy at this scale can reap many benefits.

By taking advantage of the economies of scale, all building in the plan can achieve a net energy position. In this way, an entire net zero energy district can be created. At this scale, a diverse range of strategies can be employed. District energy services can be provided efficiently, through central plants or cogeneration (com-bined heat and power) systems. Trigeneration systems that add absorption chillers for cooling with heating and power can also be considered. From a net zero energy perspective, the draw-back to cogeneration or trigeneration is that the systems typically operate on fossil fuels, such as natural gas. So, while these systems offer significant energy efficiencies, particularly from a source energy perspective, they need to be planned accordingly. Depending on the needs of the planned development, the systems can be sized to meet heating needs rather than elec-tricity needs; or a system that utilizes biomass

 ■ FIGURE 1.9 The Eastside Human Services building in Denver, Colorado, is net zero energy-ready, designed as a

low-energy building with open roof space for a future photovoltaic system installation. Image courtesy of RNL.

CERTIFYING NET ZERO ENERGY BUILDINGS ■ 15

could be considered. Large-scale renewable energy systems, such as solar farms and com-munity wind farms, are major opportunities for large-scale developments (see Figure 1.11). The renewable energy systems can be further distrib-uted through smaller-scale systems located on buildings within the development.

When looking at net zero energy on a com-munity scale, there exists an opportunity to look at net zero energy within a larger scope of interest. This can include accounting for the energy of transportation associated with the community and the energy associated with the community’s infrastructure, and indus-try energy in addition to the energy associ-ated with building operation. As NREL has worked to define and classify net zero energy buildings, in 2009 NREL published “Definition of a Zero Net Energy Community” by Nancy Carlisle, Otto Van Geet, and Shanti Pless to

further the definition and classification system in communities.

CERTIFYING NET ZERO ENERGY BUILDINGSAt the time of this writing, there was no mar-ket-accepted standard for certifying a net zero energy building. Although the metric is not dif-ficult to measure, the multiple definitions and classifications developed by NREL do indicate there are many ways to do so. Thus, currently, net zero energy achievement is typically self-reported or self-promoted. Unfortunately, most self-reported claims lack any significant detail as to how the objective was measured and met. This situation points to the need in the industry for a third-party certification program for achieving net zero energy buildings.

The current top energy-related building label and certification programs in the United States

 ■ FIGURE 1.10 The net zero energy campus planned for the Sacramento Municipal Utilities District utilizes single-axis

tracking photovoltaic canopies over the main parking lot. Image courtesy of Stantec Consulting Services Inc. and RNL.

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW16 ■

are ENERGY STAR and LEED, and neither is set up to measure and rank this level of per-formance. They could perhaps be retooled for this purpose. The International Living Future Institute launched the first-of-its-kind net zero energy certification program in October 2011, based on the institute’s Living Building Challenge certification program, discussed later in this chapter.

The Department of Energy (DOE) is dedi-cated to promoting low-energy and net zero energy buildings, and at the time of this writ-ing, it was developing a commercial building energy asset rating program as a standard way of evaluating as-built energy efficiency for buildings across the nation.

ASHRAE has a new building energy label-ing program for energy performance, called the “Building Energy Quotient,” or “Building EQ” (www.buildingeq.com). It is set up to pro-vide an operational rating based on an appraisal and application from a certified assessor. The actual label is very simple for the general public

to understand; it features a grade from A+ to F (see Figure 1.12). A project must be net zero energy to be graded A+. Behind the simple label, however, is detailed certification and sup-port documentation, which add value to both the building and real estate industries. Building EQ is voluntary but is designed in anticipation of mandatory building energy labeling programs, now proposed in locations across the United States, and similar to the system used in the United Kingdom. While Building EQ is not strictly a net zero energy certification, it does include this feature.

BUILDING INDUSTRY RESEARCH AND TRENDSMuch of the current interest and focus on energy and sustainable building practices can be attrib-uted to the success of the U.S. Green Building Council’s (USGBC’s) LEED rating system. Today, the green building market and industry expertise are becoming very sophisticated; a broad diver-sity of green building standards and programs

 ■ FIGURE 1.11 After being devastated by a tornado in 2007, the town of Greensburg, Kansas, was reconstructed

with LEED Platinum buildings and community wind power. An interior view of the new Kiowa County Schools looks out

toward a wind turbine on the horizon. Image courtesy of BNIM; photograph © 2010, Assassi.

BUILDING INDUSTRY RESEARCH AND TRENDS ■ 17

have emerged and continue to grow. And although most of the current programs are nei-ther tailored to nor focused on net zero energy, a few are, and it seems that all roads are leading to a net zero energy future.

Department of EnergyThe Department of Energy and the National Renewable Energy Laboratory have devel-oped extensive resources and conducted wide-ranging research on energy efficiency, renewable energy technologies, and the devel-opment of net zero energy buildings. Many of these resources are referenced through-out this book. The primary web portal for the DOE’s resources is through its Office of Energy Efficiency & Renewable Energy (EERE), at www .eere.energy.gov. The NREL website, which contains a searchable publication database, can be found at www.nrel.gov. As another resource, DOE also provides very detailed case studies on high-performing buildings (http://eere .buildinggreen.com) and maintains an online database on net zero energy buildings (http://zeb.buildinggreen.com).

Zero Energy Commercial Buildings ConsortiumThe Zero Energy Commercial Buildings Consortium (CBC) is a public/private entity working with the DOE to develop and deliver technologies, policies, and practices to aid the industry in realizing economically viable net zero energy buildings by 2030. This initiative supports the measures set forth in the 2007 Energy Independence and Security Act. The CBC, created in 2009, is open to membership across the industry; as of late 2011, more than 500 organizations had joined.

In early 2011, the CBC published two major reports focused on challenges and recom-mendations for the advancement of net zero energy building practices. The reports, “Next Generation Technologies Barriers and Industry

Recommendations” and “Analysis of Cost & Non-Cost Barriers and Policy Solutions,” are both available for download from the CBC web-site, www.zeroenergycbc.org. These reports address both the technical and the market barri-ers for net zero energy solutions.

New Buildings InstituteThe New Buildings Institute (NBI) is a nonprofit organization focused on providing the building industry resources and research for improved energy performance in commercial buildings. NBI has released a first-of-its-kind research paper on the current status of net zero energy build-ings in the U.S. market. The report, “Getting to Zero 2012 Status Update: A First Look at the Costs and Features of Zero Energy Commercial Buildings,” can be downloaded from the NBI website, www.newbuildings.org. For this research paper, NBI searched for a reasonably sized study group of net zero energy buildings in the United States. It found 21 with sufficient data on design,

 ■ FIGURE 1.12 Generic Label from ASHRAE’s Building

Energy Quotient Program. Image courtesy of ASHRAE.

CHAPTER 1: NET ZERO ENERGY BUILDING OVERVIEW18 ■

technologies, and measured energy use to ana-lyze (see Figures 1.13 and 1.14). NBI also identi-fied 39 cases of emerging or potential net zero energy projects, which were still under construc-tion or recently completed but without sufficient

data for review. The institute reviewed another 39 buildings that had low-enough energy use for practical consideration of adding renewables to reach net zero. For the purpose of the report, these zero energy-capable (ZEC) buildings were

Net Zero Energy Buildings Studied in NBI’s “Getting to Zero” Report

Building Type Location Square Feet

Purchased EUI

Total EUI

Data Source

2000 Oberlin College Lewis

CenterHigher Education Oberlin, OH 13,600 0 32.2 Measured

2001 Environmental Tech.

Center Sonoma StateHigher Education

Rohnert Park, CA 2,200 0 2.3 Measured

2002

Challengers Tennis Club Recreation Los Angeles,

CA 3,500 0 9.1 Modeled

Leslie Shao-Ming Sun Field Station

Higher Education Woodside, CA 13,200 3.8* 9.5* Measured

2003

Audubon Center at Debs Park

Interpretive Center

Los Angeles, CA 5,000 0 17.1 Modeled

Science House Interpretive Center St Paul, MN 1,530 0 17.6 Measured

2005 Hawaii Gateway

Energy CenterOffi ce, Interp.Center Kailua-Kona, HI 3,600 0 27.7 Measured

2007

Aldo Leopold Legacy Center

Offi ce, Interp. Center Baraboo, WI 11,900 0 15.6 Modeled

IDeAs Z2 Offi ce San Jose, CA 6,600 0 24.6 Modeled

2008

Camden Friends Meeting House Assembly Camden, DE 3,000 0 na Measured

Environmental Nature Center Assembly Newport, CA 8,535 0 17.6 Measured

Hudson Valley Clean Energy HQ

Warehouse, Offi ce Rhinebeck, NY 4,100 0 13 Measured

2009

Chrisney Library Library Chrisney, IN 2,400 0 15.3 Measured

Living Learning Center (Tyson Research Ctr)

Higher Education Eureka, MO 2,968 0 24.5 Measured

Omega Center for Sustainable Living

Interpretive Center Rhinebeck, NY 6,246 0 21 Measured

Pringle Creek Painter’s Hall Assembly Salem, OR 3,600 0 9.5 Measured

Putney Field House Recreation Putney, VT 16,800 0 9.7 Measured

2010

Energy Lab at Hawaii Preparatory Academy Education Kamuela, HI 5,902 0 11 Measured

Magnify Credit Union Offi ce Lakeland, FL 4,151 3.5 45 Measured

Richardsville Elementary K-12 Bowling Green,

KY 77,000 0 18 Modeled

NREL Research Support Facility Offi ce Golden, CO 222,000 35** 35 Modeled

Notes:EUI is kBtu/sf/yr.Total EUI includes both renewable and purchased energy.

 ■ FIGURE 1.13 Net Zero Energy Buildings in the NBI Study. Data source: New Buildings Institute, “Getting to Zero 2012 Status Update: A First Look at the Costs and Features of Zero Energy Commercial Buildings,” March 2012. Refer to www.newbuildings.org for complete report.